1. Field of the Invention
The present invention relates to an apparatus for sorting fish eggs, which apparatus is adapted to automatically sort and remove bad eggs produced during the process of incubation for fish eggs of salmons, trout and the like so as to take out only good eggs.
2. Description of the Prior Art
To cope with the volume catch of fishes with the recent modernization of fishery equipment, the exhaustion of fishes resources resulting therefrom, the restriction of offshore fishing of salmons with the recent establishment of the 200 sea miles fishery exclusive water basin, etc., every country is planning to change their policy of the fishery from the catch-only fishery to the fishery which introduces artificial enhancement or increase to gather fishes. This trend is remarkable particularly in the artificial enhancement enterprises of salmon resources. Therefore, the scale of the incubation and enhancement of salmon eggs tends to enlarge increasingly.
Also in Japan, the incubation of eggs carried out in the largest-scale salmon egg hatchery reaches 1.3 hundred million grains a season. With this, in the sorting operation of fish eggs, the number of eggs sorted in the season amounts to 4,000,000 to 5,000,000 eggs/day. It is therefore greatly desired that salmon-egg sorting apparatus is popularized and sorting apparatus itself is increased in capacity in order that the sorting capacity of salmon eggs may be enhanced.
To meet these demands as noted above, several salmon-egg sorting apparatuses have been heretofore used. For example, in one apparatus, a rotary disc is formed in the vicinity of an outer peripheral surface thereof with a number of holes to absorb fish eggs so that fish eggs are absorbed one at a time into each hole to sense and remove bad eggs. In another apparatus, a disc formed with a plurality of holes having a dimension capable of accommodating only one grain of fish egg is rotated in water in which fish eggs are floating (see Japanese Patent Publication No. 5,169/67). However, in the former, the construction thereof is complicated and the sorting capacity is about 120,000 grains/hour, and in the latter, it is necessary to change the dimension of the diameter of hole accommodating the fish egg in response to the change in size of fish egg, resulting in an extreme reduction in sorting capacity due to replacement of the fish-egg accommodating disc. In addition, the sorting capacity is merely about 100,000 grains/hour at the maximum.
These conventional apparatuses were necessary to provide with complicated mechanisms for aligning fish eggs regularly and in predetermined spaced relation to meet the capacity of the apparatus for discriminating and sorting living eggs from dead eggs. It has been however found that if the fish-egg sorting station responds quickly, sorting may be achieved without hindrance despite of the presence of unevenness in spacing to some extent or the continuous disposition as long as the fish eggs are aligned in one row. From this, the present invention has made possible to provide alignment of fish eggs in one row and quick sorting by the provision of an extremely simple device.